Composition containing aromatic nitriles for the production of transparent polythiourethane bodies

ABSTRACT

The invention relates to a composition for producing transparent polythiourethane bodies, containing or consisting of A) a polyisocyanate component that contains at least one polyisocyanate having an isocyanate group functionality of at least 2 per molecule, B) a thiol component that contains at least one polythiol having a thiol group functionality of at least 2 per molecule, and if appropriate, C) auxiliary and additional agents, the ratio of isocyanate groups to groups that are reactive to isocyanates being between 0.5:1 to 2.0:1, and said composition being characterised in that it also contains D) at least one aromatic nitrile. The invention also relates to a method for producing transparent polythiourethane bodies by reacting such a composition, to the polythiourethane bodies produced in this manner, to the use of aromatic nitriles for producing transparent polythiourethane bodies, and to a mixture of a polyisocyanate and an aromatic nitrile.

The present invention relates to compositions for producing transparentpolythiourethane articles containing or consisting of

-   A) a polyisocyanate component containing at least one polyisocyanate    having a functionality of isocyanate groups of at least 2 per    molecule,-   B) a thiol component containing at least one polythiol having a    functionality of thiol groups of at least 2 per molecule    and optionally-   C) auxiliary and additive agents,    wherein the ratio of isocyanate groups to isocyanate-reactive groups    is 0.5:1 to 2.0:1.

The invention further relates to a process for producing transparentpolythiourethane articles by reaction of such a composition and to thethus manufactured polythiourethane articles and also to the use ofaromatic nitriles for producing transparent polythiourethane articlesand, in addition, to a mixture of a polyisocyanate and an aromaticnitrile for producing compact transparent polythiourethane articles.

For various applications, for example as a lightweight substitute formineral glass for producing panes for automobile and aircraftconstruction or as embedding compositions for optical, electronic oroptoelectronic components, there is increasing interest on the markettoday in transparent, lightfast polyurethane compositions.

Particularly for high-quality optical applications, for example forlenses or spectacle glasses, there is generally a desire for plasticsmaterials exhibiting high refraction coupled with low dispersion (highAbbe number).

The production of transparent polyurethane masses having a highrefractive index has been described many times already. Araliphaticdiisocyanates, i.e. diisocyanates whose isocyanate groups are bonded viaaliphatic radicals to an aromatic system, are often used aspolyisocyanate components. Owing to their aromatic structures,araliphatic diisocyanates afford polyurethanes having an increasedrefractive index while at the same time the aliphatic isocyanate groupsguarantee the lightfastness and low yellowing tendency required forhigh-quality applications.

U.S. Pat. No. 4,680,369 and U.S. Pat. No. 4,689,387 describepolyurethanes/polythhiourethanes suitable as lens materials for example,the production of which involves combining special sulfur-containingpolyols or mercapto-functional aliphatic compounds with monomericaraliphatic diisocyanates, for example 1,3-bis(isocyanatomethyl)benzene(m-xylylene diisocyanate, m-XDI), 1,4-bis(isocyanatomethyl)benzene(p-xylylene diisocyanate, p-XDI),1,3-bis(2-isocyanatopropan-2-yl)benzene (m-tetramethylxylylenediisocyanate, m-TMXDI) or1,3-bis(isocyanatomethyl)-2,4,5,6-tetrachlorobenzene, in order toachieve particularly high refractive indices.

Monomeric araliphatic diisocyanates such as m- and p-XDI or m-TMXDI arealso mentioned in numerous further publications, for example EP-A 0 235743, EP-A 0 268 896, EP-A 0 271 839, EP-A 0 408 459, EP-A 0 506 315,EP-A 0 586 091 and EP-A 0 803 743, as the preferred polyisocyanatecomponent for producing high refractivity lens materials. They serve ascrosslinker components for polyols and/or polythiols and, depending onthe coreactant, afford transparent plastics having high refractiveindices in the range from 1.56 to 1.67 and comparatively high Abbenumbers up to 45.

A substantial disadvantage of the mentioned processes for producing highrefractivity polyurethanes/polythiourethanes for optical applications isthat the reaction between polythiols and polyisocyanates is highlysensitive to impurities with the result that some of the manufacturedlenses do not always meet the desired standards in terms of theirtransparency and freedom from cloudiness. This applies especially toapplication in lenses and the like.

The present invention accordingly has for its object to specify acomposition for producing transparent polythiourethane articles whichmakes it possible to manufacture such articles with improved opticalproperties, in particular improved transparency and freedom fromcloudiness.

This object is achieved in a composition of the type mentioned at theoutset when the composition further contains D) at least one aromaticnitrile.

The present invention accordingly provides a composition for producingtransparent polythiourethane articles containing or consisting of

-   A) a polyisocyanate component containing at least one polyisocyanate    having a functionality of isocyanate groups of at least 2 per    molecule,-   B) a thiol component containing or consisting of at least one    polythiol having a    -   functionality of thiol groups of at least 2 per molecule and        optionally-   C) auxiliary and additive agents,    wherein the ratio of isocyanate groups to isocyanate-reactive groups    is 0.5:1 to 2.0:1,    wherein the composition is characterized in that    the composition further contains-   D) at least one aromatic nitrile.

In the context of the present invention, the term “transparent” is to beunderstood as meaning that the transparent article has a transmittanceof ≧85% for a thickness of 2 mm and standard light type D65 (defined inDIN 6173). However, this transmittance value can deviate from theaforementioned value of ≧85% in the case of optional co-use of UVstabilizers and dyes.

The present invention is based on the finding that the presence of atleast one aromatic nitrile in compositions of the type described at theoutset has the result that in further processing to affordpolythiourethanes the thus manufactured molded articles suffer fromcloudiness much less frequently. Without wishing to be bound to aparticular theory it is believed that the nitriles may either react withthe thiols or act as solubility promoters for dimers or trimers of thepolyisocyanate that are being formed. Without the nitrile these couldprecipitate which could be a possible reason for the cloudiness thatoccurs.

A further advantage is that the composition according to the inventionis less sensitive to entrained water than prior art systems as aredescribed in U.S. Pat. No. 8,044,165 B2 for example. Normally, the thiolcomponent in particular must be dried to remove excess water which couldotherwise impair the optical properties of manufactured opticalcomponents. By contrast this is not necessary for the present invention.Thus the water content of the thiol component in the compositionsaccording to the invention may be >600 ppm, in particular >800 ppm oreven more than 900 ppm.

There are various options for introducing the aromatic nitrile into thecomposition. The nitrile addition may preferably be effected duringformulation of the composition, it being particularly preferable whenthe nitrile is premixed with the polyisocyanate component before thereaction with the thiol component is effected. However, the invention isin no way limited to this option. Thus, nitrile addition may also beeffected before or during manufacture of the polyisocyanate which istypically effected by a liquid-phase or gas-phase phosgenation of thecorresponding polyamines. The addition of portions of the aromaticnitrile at any desired timepoints is also possible.

It is further possible to add portions or the total amount of thearomatic nitriles only during mixing of the reactive components or topremix said portions or entirety with the thiol component.

It is also possible—aside from the previously described active additionof the aromatic nitriles—to manufacture a portion or else the totalamount of aromatic nitriles in situ. This is achieved via a gas-phasephosgenation of araliphatic polyamines to afford the correspondingaraliphatic polyisocyanates. Unlike liquid-phase phosgenation this formsaromatic nitriles as byproducts of the phosgenation. This option is verypreferably applied in the gas-phase phosgenation of 1,3-xylylenediamine(1,3-XDA) and/or 1,4-xylylenediamine (1,4-XDA) to afford1,3-bis(isocyanatomethyl)benzene (1,3-XDI) and/or1,4-bis(isocyanatomethyl)benzene (1,4-XDI). Depending on the desirednitrile amount the thus manufactured araliphatic diisocyanate or amixture of the compounds mentioned with the production-dependent amountof aromatic nitriles present may be employed in a composition accordingto the invention or else the nitrile amount may be increased by additionof further aromatic nitriles which may be identical or different to thenitriles present.

In principle the compositions according to the invention may contain notonly the aromatic nitriles but, in addition, also other organicnitriles, for example aliphatic, cycloaliphatic or araliphatic nitriles.

The invention provides that the polyisocyanate component contains atleast one polyisocyanate having at least two isocyanate groups permolecule, in particular from 2 to 6, preferably from 2 to 4,particularly preferably from 2 to 3. It is also possible to employmixtures of polyisocyanates of different functionality and odd-numberedaverage functionalities may therefore arise. In the context of thepresent invention the term polyisocyanate is to be understood as meaningorganic isocyanates having two or more free isocyanate groups. Thepolyisocyanate may be in monomeric form or else in oligomeric form.Modification reactions suitable therefor are for example the customaryprocesses for catalytic oligomerization of isocyanates to formuretdione, isocyanurate, iminooxadiazinedione and/or oxadiazinetrionestructures or for biuretization of diisocyanates such as are describedby way of example in Laas et al., J. Prakt. Chem. 336, 1994, 185-200, inDE-A 1 670 666 and in EP-A 0 798 299 for example. Specific descriptionsof such poly-isocyanates based on araliphatic diisocyanates may also befound in EP-A 0 081 713, EP-A 0 197 543, GB-A 1 034 152 and JP-A05286978 for example. The syllable “poly” accordingly relatesessentially to the number of isocyanate groups per molecule and does notnecessarily mean that the polyisocyanate must have an oligomeric, muchless a polymeric, structure.

Polyisocyanates that may be employed in the context of the presentinvention in principle include all polyisocyanates known per se. Theseare for example polyisocyanates in the molecular weight range 140 to 400g/mol, for example 1,4-diisocyanatobutane, 1,5-diisocyanatopentane,1,6-diisocyanatohexane (HDI), 1,5-diisocyanato-2,2-dimethylpentane,2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane,1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane,1,3- and 1,4-diisocyanatocyclohexane,1,4-diisocyanato-3,3,5-trimethylcyclohexane,1,3-diisocyanato-2-methylcyclohexane,1,3-diisocyanato-4-methylcyclohexane,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophoronediisocyanate; IPDI),1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane, 2,4′- and4,4′-diisocyanatodicyclohexylmethane (H₁₂-MDI), 1,3- and1,4-bis(isocyanatomethyl)cyclohexane,2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane,2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane,4,4′-diisocyanato-3,3′-dimethyldicyclohexylmethane,4,4′-diisocyanato-3,3′,5,5′-tetramethyldicyclohexylmethane,4,4′-diisocyanato-1,1′-bi(cyclohexyl),4,4′-diisocyanato-3,3′-dimethyl-1,1′-bi(cyclohexyl),4,4′-diisocyanato-2,2′,5,5′-tetramethyl-1,1′-bi(cyclohexyl),1,8-diisocyanato-p-menthane, 1,3-diisocyanatoadamantane,1,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and1,4-bis(isocyanatomethyl)benzene, 1,3- and1,4-bis(1-isocyanato-1-methylethyl)benzene (TMXDI),bis(4-(1-isocyanato-1-methylethyl)phenyl) carbonate, phenylene 1,3- and1,4-diisocyanate, tolylene 2,4- and 2,6-diisocyanate and any desiredmixtures of these isomers, diphenylmethane 2,4′- and/or4,4′-diisocyanate and naphthylene 1,5-diisocyanate and any desiredmixtures of such diisocyanates.

These polyisocyanates may have been produced by any desired processes,for example by phosgenation of the corresponding amines in the gas orliquid phase but also by phosgene-free methods, for example by carbamatecleavage.

The polyisocyanates are preferably selected from1,3-bis(isocyanatomethyl)benzene (1,3-XDI),1,4-bis(isocyanatomethyl)benzene (1,4-XDI),2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane,2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane,1,4-bis(isocyanatomethyl)cyclohexane,1,3-bis(isocyanatomethyl)cyclohexane,2,2′-diisocyanatodicyclohexylmethane,2,4′-diisocyanatodicyclohexylmethane,4,4′-diisocyanatodicyclohexylmethane (H12-MDI),1-isocyanato-3,3,5-trimethyl-5-isocyanato ethylcyclohexane(isophoronediisocyanate; IPDI) or mixtures thereof, especiallypreferably 1,3-bis(isocyanatomethyl)benzene (1,3-XDI) and/or1,4-bis(isocyanatomethyl)benzene (1,4-XDI). These poly- anddiisocyanates are preferred because they make it possible to obtain lensmaterials having particularly good optical properties, such as a highrefractive index and high transparency. These advantages areparticularly pronounced for the diisocyanates mentioned as preferable1,3-bis(isocyanatomethyl)benzene (1,3-XDI) and1,4-bis(isocyanatomethyl)benzene (1,4-XDI).

The average isocyanate functionality of the polyisocyanate component A)is preferably 1.8 to 4.0, in particular 1.9 to 3.5, particularlypreferably 2.0 to 3.0.

The present invention may provide that at least one polyisocyanate ofthe polyisocyanate component A) has been produced by gas-phasephosgenation of aliphatic, cycloaliphatic, aromatic or araliphaticpolyamines. Such a process for manufacturing the polyisocyanates to beemployed in accordance with the invention is described in EP 1 754 698B1. Also employable is a process for gas-phase phosgenation as isdisclosed in WO 2013/079517 A1.

The gas phase phosgenation procedure is preferably conducted such thatthe relevant starting substances, i.e. the polyamines upon which thepolyisocyanates to be produced are based, are evaporated, optionallywith addition of stabilizers and/or an inert gas, this being done at apressure of <1000 mbar if necessary. The polyamines evaporated in thisway are passed through a circuit with an average residence time of 5 to90 minutes and a temperature of 40° C. to 190° C. and reacted withphosgene in accordance with processes of gas-phase phosgenation knownper se at a temperature of 10 to 100 K above the evaporation temperatureof the amines at the prevailing pressure. The above process conditionsapply in particular to the manufacture of 1,3-xylylenediisocyanate and1,4-xylylenediisocyanate. In this way, comparatively large amounts ofnitrile are formed which have an advantageous effect on furtherprocessing in a composition according to the invention, in particular interms of the transparency of molded articles manufactured therefrom. Inthis case—depending on the desired content of aromatic nitriles in thecomposition—active addition of aromatic nitriles may be eschewed forthis embodiment.

Suitable modification reactions for producing the polyisocyanatecomponents A) are, if desired, urethanization and/or allophanatizationof araliphatic diisocyanates after addition of a molar deficiency ofhydroxyl-functional coreactants, in particular low molecular weightmono- or polyhdric alcohols in the molecular weight range 32 to 300g/mol, for example methanol, ethanol, n-propanol, isopropanol,n-butanol, isobutanol, secbutanol, the isomeric pentanols, hexanols,octanols and nonanols, n-decanol, ndodecanol, n-tetradecanol,n-hexadecanol, n-octadecanol, cyclohexanol, the isomericmethylcyclohexanols, hydroxymethylcyclohexane,3-methyl-3-hydroxymethyloxetane, 1,2-ethanediol, 1,2- and1,3-propanediol, the isomeric butanediols, pentanediols, hexanediols,heptanediols and octanediols, 1,2- and 1,4-cyclohexanediol,1,4-cyclohexanedimethanol, 4,4′-(1-methylethylidene)biscyclohexanol,diethylene glycol, dipropylene glycol, 1,2,3-propanetriol,1,1,1-trimethylolethane, 1,2,6-hexanetriol, 1,1,1-trimethylolpropane,2,2-bis(hydroxymethyl)-1,3-propanediol or1,3,5-tris(2-hydroxyethyl)isocyanurate, or any desired mixtures of suchalcohols. Preferred alcohols for producing urethane- and/orallophanate-modified polyisocyanate components A) are the mentionedmonoalcohols and diols having 2 to 8 carbon atoms.

Specific descriptions of urethane- and/or allophanate-modifiedpolyisocyanates based on araliphatic diisocyanates may be found in EP-A1 437 371, EP-A 1 443 067, JP-A 2005161611691, JP-A 2005162271 forexample.

If one or more polyisocyanates manufactured via gas-phase phosgenationare to be employed for the composition according to the invention, apreferred configuration of the composition according to the inventionspecifies that the polyisocyanate component contains at least 30 wt %based on the polyisocyanate component of polyisocyanate produced bygas-phase phosgenation, in particular at least 50 wt %, more preferablyat least 80 wt % or even at least 90 wt %, particularly preferably atleast 95 wt % or even at least 96 or at least 98 wt %.

When polyisocyanate manufactured by gas-phase phosgenation is employedit is preferable for least one nitrile present as a byproduct in thepolyisocyanate component present by gas-phase phosgenation to form afurther constituent of the polyisocyanate component. In addition to thepolyisocyanate manufactured by gas-phase phosgenation the polyisocyanatecomponent may quite possibly also have had a polyisocyanate manufacturedby a different production route added to it, for example apolyisocyanate produced by liquid-phase phosgenation.

Depending on the nitrile content of the polyisocyanate component theproportion of polyisocyanates produced by routes other than gas-phasephosgenation may be for example up to 19 wt % based on thepolyisocyanate component A), or else up to 14 wt %, up to 9 wt %, up to4 wt % or up to 3 wt %.

In a preferred embodiment of the composition according to the inventionin which at least one polyisocyanate manufactured by gas-phasephosgenation is employed the polyisocyanate component contains at least0.005 wt % based on the polyisocyanate component A) of at least onearomatic nitrile, in particular at least 0.01 wt %, preferably 0.005 to15 wt %, more preferably 0.01 to 5 wt %, particularly preferably 0.1 to2 wt % or even 0.1 to 1 wt %.

As already stated hereinabove the polyisocyanate components employed inaccordance with the invention and manufactured by gas-phase phosgenationmay already contain a certain proportion of nitriles as a result of theproduction process which may be influenced inter alia by the nature ofthe polyamines employed in the reaction and moreover by the choice ofthe reaction conditions, in particular the pressure and the reactiontemperature. This applies in particular for the polyisocyanatesparticularly preferred in the context of the present invention1,3-bis(isocyanatomethyl)benzene (1,3-XDI) and1,4-bis(isocyanatomethyl)benzene (1,4-XDI) which after the gas-phasephosgenation generally exhibit comparatively high contents ofcorresponding nitriles.

Independently of the presence of one or more polyisocyanates produced bygas-phase phosgenation the composition preferably contains 0.0025 to 10wt % based on the total composition of aromatic nitrile, in particular0.005 to 5 wt %, more preferably 0.01 to 3 wt % and particularlypreferably 0.05 to 2 wt %. These usage quantities of aromaticnitriles—regardless of whether they are present as a byproduct of thegas phase phosgenation or are entirely or partly actively added—areparticularly advantageous because this makes it possible to produceoptical molded articles that are particularly transparent and free fromcloudiness from polythiourethanes, for example lenses.

In the context of the present invention the content of nitriles isdetermined by derivatization with diethylamine and subsequent HPLC-MS byintegration of the areas of the signals in the UV range. The HPLC-MSmeasurement may be performed with the following program for example:

Synapt G2-S HR-MS, ACQUITY UPLC (Waters) QS. No.: 02634

UV: PDA (Total Absorbance Chromatogram)

Column: Kinetex 100×2.1 mm_1.7 μm

Column temperature: 30° C.

The mobile phase consisted of:

Solvent: A) water+0.05% formic acid

B) acetonitrile+0.05% formic acid

Flow rate: 0.5 ml/min

Gradient: t0/5% B_t0.5/5% B_t6/100% B_t7/100% B_t7.1/5% B_t8/5% B

In the context of the present invention it is preferable when thenitrile is derived from the same polyamine as the polyisocyanate. Thisapplies both for the nitriles present as a result of the productionprocess and for any subsequently added nitriles. This is particularlyadvantageous since the identical basic chemical structure to that of thepolyisocyanate manufactured during the gas-phase phosgenation ensuresthat a particularly good promotion effect is achieved by the nitrile.

It is moreover particularly preferable for the nitrile to contain atleast one further functional group which is in particular a group thatcan be incorporated into the polythiourethane network to prevent latermigration of the nitrile out of the molded article and may particularlypreferably be an isocyanate group. This shall be elucidated hereinbelowwith reference to the example 1,3-bis(isocyanatomethyl)benzene(1,3-XDI). This diisocyanate may be manufactured by gas-phasephosgenation of 1,3-bis(aminomethyl)benzene. The particularly preferredisocyanatonitrile in this case is 3-(isocyantomethyl)benzonitrile.

The reaction of such an isocyanatonitrile with the thiol component canform nitrile-modified thiourethanes. This is shown using the example of3-(isocyantomethyl)benzonitrile.

Here, R2 represents the radical of the polythiol employed. For4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (DMPT) the radical R2represents the following structural unit, wherein the left-hand bondline in the formula represents the bond to the sulfur atom in the abovestructure.

It is also possible for both thiol groups of the DMPT to react with onemolecule of 3-(isocyantomethyl)benzonitrile respectively, thus formingthe structure:

Analogous compounds may also be formed with optionally employed polyols.First, in general terms, the reaction product of3-(isocyantomethyl)benzonitrile with a polyol where R1 represents theradical of the polyol employed:

A nitrile-modified urethane is thus formed. When a diol is employed itis also possible for both OH groups to react with one molecule of3-(isocyantomethyl)benzonitrile respectively, thus forming thestructure:

In the context of the present invention the term aromatic nitriles is tobe understood as meaning compounds having a nitrile group bondeddirectly to an aromatic and preferably having a molar mass of <1000g/mol, particularly preferably <500 g/mol.

In a preferred configuration of the composition according to theinvention the nitrile is selected from benzonitrile,3-(isocyanatomethyl)benzonitrile, 4-(isocyanatomethyl)benzonitrile,3-(chloromethyl)benzonitrile, 4-(chloromethyl)benzonitrile,3-cyanobenzoic acid, 4-cyanobenzoic acid, 2-hydroxybenzonitrile,3-hydroxybenzonitrile, 4-hydroxybenzonitrile, 3-cyanobenzoyl chloride,4-cyanobenzoyl chloride or mixtures thereof, in particular benzonitrile,3-(chloromethyl)benzonitrile, 4-(chloromethyl)benzonitrile,3-(isocyanatomethyl)benzonitrile, and/or4-(isocyanatomethyl)benzonitrile, particularly preferably3-(isocyanatomethyl)benzonitrile, and/or4-(isocyanatomethyl)benzonitrile. The use of these nitriles isadvantageous particularly when a polyisocyanate component which hasrelatively large proportions of 1,3-XDI and/or 1,4-XDI, such as >50 wt %based on the polyisocyanate component A), or which in terms of thepolyisocyanates consists completely of these compounds, is used. Inthese cases a particularly pronounced improvement in the opticalproperties of a polythiourethane article manufactured therefrom may beobserved, especially as regards transparency thereof.

In a particularly preferred embodiment of the composition according tothe invention the polyisocyanate is selected from1,3-bis(isocyanatomethyl)benzene (1,3-XDI) and the nitrile from3-(isocyanatomethyl)benzonitrile and/or that the polyisocyanate isselected from 1,4-bis(isocyanatomethyl)benzene (1,4-XDI) and the nitrilefrom 4-(isocyanatomethyl)benzonitrile.

The composition according to the invention further contains a thiolcomponent B). Said component contains or consists of at least onepolythiol having a functionality of thiol groups of at least two permolecule, in particular from 2 to 6, preferably from 2 to 4,particularly preferably from 3 to 4. It is also possible to employmixtures of polythiols of different functionality and odd-numberedaverage functionalities may therefore arise. In the context of thepresent invention the term polythiol is to be understood as meaningorganic thiols having two or more thiol groups. The syllable “poly”accordingly relates essentially to the number of thiol groups permolecule and, as stated above for the polyisocyanate compounds, does notnecessarily mean that the polythiol must have an oligomeric, much less apolymeric, structure. Notwithstanding, the polythiols used according tothe invention may quite possibly also have a polyether basic structure,a polythioether basic structure or a mixed basic structure composed ofO-ether and S-ether units.

The polythiol may have an average molecular weight of 80(methanedithiol) to about 12000 g/mol, preferably 250 to 8000 g/mol.

Suitable polythiols include for example methanedithiol,1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol,1,3-propanedithiol, 2,2-propanedithiol, 1,4-butanedithiol,2,3-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol,1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol,2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol and2-methylcyclohexane-2,3-dithiol, polythiols containing thioether groups,for example 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane,4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane,4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,5-bis(mercaptoethylthio)-1,10-dimercapto-3,8-dithiadecane,tetrakis(mercaptoethyl)methyl)methane,1,1,3,3-tetrakis(mercaptomethylthio)propane,1,1,5,5-tetrakis(mercaptomethylthio)-3-thiapentane,1,1,6,6-tetrakis(mercaptomethylthio)-3,4-dithiahexane,2-mercaptoethylthio-1,3-dimercaptopropane,2,3-bis(mercaptoethylthio)-1-mercaptopropane,2,2-bis(mercaptomethyl)-1,3-dimercaptopropane, bis(mercaptomethyl)sulfide, bis(mercaptomethyl) disulfide, bis(mercaptoethyl) sulfide,bis(mercaptoethyl) disulfide, bis(mercaptopropyl) sulfide,bis(mercaptoproropyl) disulfide, bis-(mercaptomethylthio)methane,tris(mercaptomethylthio)methane, bis(mercaptoethylthio)methane,tris(mercaptoethylthio)methane, bis(mercaptopropylthio)methane,1,2-bis(mercaptomethylthio)ethane, 1,2-bis(mercaptoethylthio)ethane,2-(mercaptoethltthio)ethane, 1,3-bis(mercaptomethylthio)propane,1,3-bis(mercaptopropylthio)propane,1,2,3-tris(mercaptomethylthio)propane,1,2,3-tris(mercaptoethylthio)propane,1,2,3-tris(mercaptopropylthio)propane,tetrakis(mercaptomethylthio)methane,tetrakis(mercaptoethylthiomethyl)methane,tetrakis(mercaptopropylthiomethyl)methane, 2,5-dimercapto-1,4-dithiane,2,5-bis(mercaptomethyl)-1,4-dithiane and oligomers thereof obtainable asdescribed in JP-A 07118263, 1,5-bis(mercaptopropyl)-1,4-dithiane,1,5-bis(2-mercaptoethylthiomethyl)-1,4-dithiane,2-mercaptomethyl-6-mercapto-1,4-dithiacycloheptane,2,4,6-trimercapto-1,3,5-trithiane,2,4,6-trimercaptomethyl-1,3,5-trithiane and2-(3-bis(mercaptomethyl)-2-thiapropyl)-1,3-dithiolane, polyester thiols,for example ethylene glycol bis(2-mercaptoacetate), ethylene glycolbis(3-mercaptopropionate), diethylene glycol 2-mercaptoacetate,diethylene glycol 3-mercaptopropionate, 2,3-dimercapto-1-propanol3-mercaptopropionate, 3-mercapto-1,2-propanediol bis(2-mercaptoacetate),3-mercapto-1,2-propanediol bis(3-mercaptopropionate), trimethylolpropanetris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate),trimethylolethane tris(2-mercaptoacetate), trimethylolethanetris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate),pentaerythritol tetrakis(3-mercaptopropionate), glyceroltris(2-mercaptoacetate), glycerol tris(3-mercaptopropionate),1,4-cyclohexanediol bis(2-mercaptoacetate), 1,4-cyclohexanediolbis(3-mercaptopropionate), hydroxymethyl sulfide bis(2-mercaptoacetate),hydroxymethyl sulfide bis(3-mercaptopropionate), hydroxyethyl sulfide2-mercaptoacetate, hydroxyethyl sulfide 3-mercaptopropionate,hydroxymethyl disulfide 2-mercaptoacetate, hydroxymethyl disulfide3-mercaptopropionate, 2-mercaptoethyl ester thioglycolate andbis(2-mercaptoethyl ester) thiodipropionate and also aromatic thiocompounds, for example 1,2-dimercaptobenzene, 1,3-dimercaptobenzene,1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene,1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene,1,4-bis(mercaptoethyl)benzene, 1,2,3-trimercaptobenzene,1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene,1,2,3-tris(mercaptomethyl)benzene, 1,2,4-tris(mercaptomethyl)benzene,1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene,1,3,5-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene,2,5-toluenedithiol, 3,4-toluenedithiol, 1,4-naphthalenedithiol,1,5-naphthalenedithiol, 2,6-naphthalenedithiol, 2,7-naphthalenedithiol,1,2,3,4-tetramercaptobenzene, 1,2,3,5-tetramercaptobenzene,1,2,4,5-tetramercaptobenzene, 1,2,3,4-tetrakis(mercaptomethyl)benzene,1,2,3,5-tetrakis(mercaptomethyl)benzene,1,2,4,5-tetrakis(mercaptomethyl)benzene,1,2,3,4-tetrakis(mercaptoethyl)benzene,1,2,3,5-tetrakis(mercaptoethyl)benzene,1,2,4,5-tetrakis(mercaptoethyl)benzene, 2,2′-dimercaptobiphenyl and4,4′-dimercaptobiphenyl.

It is preferable when the polythiol is selected from4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane,2,5-bismercaptomethyl-1,4-dithiane,1,1,3,3-tetrakis(mercaptomethylthio)propane,5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,trimethylolpropane tris(3-mercaptopropionate), trimethylolethanetris(2-mercaptoacetate), pentaerythritol tetrakis(2-mercaptoacetate)and/or pentaerythritol tetrakis(3-mercaptopropionate).

Aside from the thiol component B) the composition according to theinvention may also contain other components typically reacted withpolyisocyanates. These are in particular the customary polyetherpolyols,polyesterpolyols, polyetherpolyesterpolyols, polythioetherpolyols,polymer-modified polyetherpolyols, graft polyetherpolyols, in particularthose based on styrene and/or acrylonitrile, polyetherpolyamines,hydroxyl-containing polyacetals and/or hydroxyl-containing aliphaticpolycarbonates known from polyurethane chemistry which typically have aweight-average molecular weight of 106 to 12 000 g/mol, preferably 250to 8000 g/mol. A broad overview of suitable coreactants B) may be foundfor example in N. Adam et al.: “Polyurethanes”, Ulhnann's Encyclopediaof Industrial Chemistry, Electronic Release, 7th ed., chap. 3.2-3.4,Wiley-VCH, Weinheim 2005.

In the context of the present invention the term polythiourethane is tobe understood as meaning a polymer where more than half to all of thebonds between the polyisocyanate and the isocyanate-reactivecomponent(s) are thiourethane groups. Thus, other bonds may be presentin a proportion of less than half, for example urethane or urea bridges.In this case the composition according to the invention also containsother isocyanate-reactive component(s). These merely optional componentsare more particularly described hereinbelow.

Suitable polyetherpolyols, if used, are for example those of the typereferred to in DE-A 2 622 951, column 6, line 65-column 7, line 47, orEP-A 0 978 523, page 4, line 45 to page 5, line 14, provided that theyconform to the above indications relating to functionality and molecularweight. Particularly preferred polyetherpolyols B) are addition productsof ethylene oxide and/or propylene oxide onto glycerol,trimethylolpropane, ethylenediamine and/or pentaerythritol.

Suitable polyesterpolyols, if used, are for example those of the typereferred to in EP-A 0 978 523, page 5, lines 17 to 47, or EP-A 0 659792, page 6, lines 8 to 19, provided that they conform to the aboveindications, preferably those having a hydroxyl number of 20 to 650 mgKOH/g.

Suitable polyacetalpolyols, if used, are for example the known reactionproducts of simple glycols, for example diethylene glycol, triethyleneglycol, 4,4′-dioxyethoxydiphenyldimethylmethane (adduct of 2 mol ofethylene oxide onto bisphenol A) or hexanediol, with formaldehyde, orelse polyacetals produced by polycondensation of cyclic acetals, forexample trioxane.

Aminopolyethers or mixtures of aminopolyethers may likewise be suitable,i.e. polyethers having isocyanate-reactive groups which are composed ofprimary and/or secondary, aromatic or aliphatic amino groups to anextent of at least 50 equivalent %, preferably at least 80 equivalent %,and of primary and/or secondary, aliphatic hydroxyl groups as theremainder. Suitable aminopolyethers of this type are for example thecompounds referred to in EP-A 0 081 701, column 4, line 26 to column 5,line 40. Likewise suitable as starting component E) are amino-functionalpolyetherurethanes or -ureas such as are producible for example by theprocess of DE-A 2 948 419 by hydrolysis of isocyanate-functionalpolyether prepolymers or else amino-containing polyesters of theabovementioned molecular weight range.

Further suitable isocyanate-reactive components are, for example, alsothose described in EP-A 0 689 556 and EP-A 0 937 110, for examplespecial polyols obtainable by reaction of epoxidized fatty acid esterswith aliphatic or aromatic polyols to bring about epoxide ring opening.

Hydroxyl-containing polybutadienes too may optionally be employed.

Sulfur-containing hydroxyl compounds are moreover also suitable asisocyanate-reactive components. Examples that may be mentioned here aremercaptoalcohols, for example 2-mercaptoethanol, 3-mercaptopropanol,1,3-dimercapto-2-propanol, 2,3-dimercaptopropanol and dithioerythritol,thioether-containing alcohols, for example di(2-hydroxyethyl)sulfide,1,2-bis(2-hydroxyethylmercapto)ethane, bis(2-hydroxyethyl)disulfide and1,4-dithiane-2,5-diol, or sulfur-containing diols having apolyesterurethane-, polythioesterurethane-, polyesterthiourethane- orPolythioesterthiourethane structure of the type referred to in EP-A 1640 394.

The compositions according to the invention may also contain asisocyanate-reactive compounds low molecular weight, hydroxyl- and/oramino-functional components, i.e. those in a molecular weight range from60 to 500 g/mol, preferably from 62 to 400 g/mol.

These are for example simple mono- or polyhydric alcohols having 2 to14, preferably 4 to 10 carbon atoms, for example 1,2-ethanediol, 1,2-and 1,3-propanediol, the isomeric butanediols, pentanediols,hexanediols, heptanediols and octanediols, 1,10-decanediol, 1,2- and1,4-cyclohexanediol, 1,4-cyclohexanedimethanol,4,4′-(1-methylethylidene)biscyclohexanol, 1,2,3-propanetriol,1,1,1-trimethylolethane, 1,2,6-hexanetriol, 1,1,1-trimethylolpropane,2,2-bis(hydroxymethyl)-1,3-propanediol, bis(2-hydroxyethyl)hydroquinone,1,2,4- and 1,3,5-trihydroxycyclohexane or1,3,5-tris(2-hydroxyethyl)isocyanurate.

Examples of suitable low molecular weight amino-functional compounds arealiphatic and cycloaliphatic amines and aminoalcohols having primaryand/or secondary amino groups, for example cyclohexylamine,2-methyl-1,5-pentanediamine, diethanolamine, monoethanolamine,propylamine, butylamine, dibutylamine, hexylamine, monoisopropanolamine,diisopropanolamine, ethylenediamine, 1,3-diaminopropane,1,4-diaminobutane, isophoronediamine, diethylenetriamine, ethanolamine,aminoethylethanolamine, diaminocyclohexane, hexamethylenediamine,methyliminobispropylarmine, iminobispropylamine,bis(aminopropyl)piperazine, aminoethylpiperazine,1,2-diaminocyclohexane, triethylenetetramine, tetraethylenepentamine,1,8-p-diaminomenthane, bis(4-aminocyclohexyl)methane,bis(4-amino-3-methylcyclohexyl)methane,bis(4-amino-3,5-dimethylcyclohexyl)methane,bis(4-amino-2,3,5-trimethylcyclohexyl)methane,1,1-bis(4-aminocyclohexyl)propane, 2,2-bis(4-aminocyclohexyl)propane,1,1-bis(4-aminocyclohexyl)ethane, 1,1-bis(4-aminocyclohexyl)butane,2,2-bis(4-aminocyclohexyl)butane,1,1-bis(4-amino-3-methylcyclohexyl)ethane,2,2-bis(4-amino-3-methylcyclohexyl)propane,1,1-bis(4-amino-3,5-dimethylcyclohexyl)ethane,2,2-bis(4-amino-3,5-dimethylcyclohexyl)propane,2,2-bis(4-amino-3,5-dimethylcyclohexyl)butane,2,4-diaminodicyclohexylmethane,4-aminocyclohexyl-4-amino-3-methylcyclohexylmethane,4-amino-3,5-dimethylcyclohexyl-4-amino-3-methylcyclohexylmethane and2-(4-aminocyclohexyl)-2-(4-amino-3-methylcyclohexyl)methane.

Examples of aromatic polyamines, in particular diamines, havingmolecular weights below 500 which are suitable isocyanate-reactivecompounds B) are for example 1,2- and 1,4-diaminobenzene, 2,4- and2,6-diaminotoluene, 2,4′- and/or 4,4′-diaminodiphenylmethane,1,5-diaminonaphthalene, 4,4′,4″-triaminotriphenylmethane,4,4′-bis(methylamino)diphenylmethane or1-methyl-2-methylamino-4-aminobenzene,1-methyl-3,5-diethyl-2,4-diaminobenzene,1-methyl-3,5-diethyl-2,6-diaminobenzene,1,3,5-trimethyl-2,4-diaminobenzene, 1,3,5-triethyl-2,4-diaminobenzene,3,5,3′,5′-tetraethyl-4,4′-diaminodiphenylmethane,3,5,3′,5′-tetraisopropyl-4,4′-diaminodiphenylmethane,3,5-diethyl-3′,5′-diisopropyl-4,4′-diaminodiphenylmethane,3,3′-diethyl-5,5′-diisopropyl-4,4′-diaminodiphenylmethane,1-methyl-2,6-diamino-3-isopropylbenzene, liquid mixtures ofpolyphenylpolymethylenepolyamines, such as are obtainable in knownfashion by condensation of aniline with formaldehyde, and any desiredmixtures of such polyamines. In this connection particular mention maybe made of mixtures of 1-methyl-3,5-diethyl-2,4-diaminobenzene with1-methyl-3,5-diethyl-2,6-diaminobenzene in a weight ratio of 50:50 to85:15, preferably of 65:35 to 80:20.

The use of low molecular weight amino-functional polyethers havingmolecular weights below 500 g/mol is likewise possible. These are forexample those which have primary and/or secondary, aromatic or aliphaticamino groups, said amino groups optionally being bonded to the polyetherchains via urethane or ester groups, and which are obtainable by knownprocesses already described above in connection with production of thehigher molecular weight aminopolyethers.

Sterically hindered aliphatic diamines having two secondary amino groupsmay optionally also be employed as isocyanate-reactive components, forexample the reaction products of aliphatic and/or cycloaliphaticdiamines with maleic or fumaric esters disclosed in EP-A 0 403 921 orthe hydrogenation products of Schiff bases obtainable from aliphaticand/or cycloaliphatic diamines and ketones, for example diisopropylketone, described in DE-A 19 701 835 for example.

In addition to the mentioned starting components A) and B), auxiliaryand additive agents (C), for example catalysts, surface-active agents,UV stabilizers, antioxidants, fragrances, mold release agents, fillersand/or pigments, may optionally be co-used.

For the purpose of reaction acceleration it is possible to employ, forexample, customary catalysts known from polyurethane chemistry. By wayof example mention may be made here of tertiary amines, for exampletriethylamine, tributylamine, dimethylbenzylamine, diethylbenzylamine,pyridine, methylpyridine, dicyclohexylmethylamine,dimethylcyclohexylamine, N,N,N′,N′-tetramethyldiaminodiethyl ether,bis(dimethylaminopropyl)urea, N-methyl-1 N-ethylmorpholine,N-cocomorpholine, N-cyclohexylmorpholine,N,N,N,N′-tetramethylethylenediamine,N,N,N′,N′-tetramethyl-1,3-butanediamine,N,N,N′,N′-tetramethyl-1,6-hexanediamine, pentamethyldiethylenetriamine,N-methylpiperidine, N-dimethylaminoethylpiperidine,N,N′-dimethylpiperazine, N-methyl-N′-dimnethylaminopiperazine,1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), 1,2-dimethylimidazole,2-methylimidazole, N,N-dimethylimidazol-phenylethylamine,1,4-diazabicyclo-(2,2,2)-octane, bis(N,N-dimethylaminoethyl)adipate;alkanolamine compounds, for example triethanolamine,triisopropanolamine, N-methyl- and N-ethyldiethanolamine,dimethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol,N,N′,N″-tris(dialkylaminoalkyl)hexahydrotriazines, for exampleN,N′,N″-tris(dimethylaminopropyl)-s-hexahydrotriazine and/orbis(dimethylaminoethyl) ether; metal salts, for example inorganic and/ororganic compounds of iron, lead, bismuth, zinc and/or tin in customaryoxidation states of the metal, for example iron(II) chloride, iron(III)chloride, bismuth(II) bismuth(III) 2-ethylhexanoate, bismuth(III)octoate, bismuth(III) neodecanoate, zinc chloride, zinc 2-ethylcaproate,tin(II) octoate, tin(II) ethylcaproate, tin(II) palmitate,dibutyltin(IV) dilaurate (DBTL), dibutyltin(IV) dichloride,dimethyltin(IV) dichloride or lead octoate; amidines, for example2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tetraalkylammoniumhydroxides, for example tetramethylammonium hydroxide; alkali metalhydroxides, for example sodium hydroxide, and alkali metal alkoxides,for example sodium methoxide and potassium isopropoxide, and also alkalimetal salts of long-chain fatty acids having 10 to 20 carbon atoms andoptionally lateral OH groups.

Preferred catalysts C) for use are tertiary amines, bismuth and tincompounds of the type mentioned.

The catalysts mentioned by way of example may be used in the productionof the lightfast polyurethane, polythiourethane and/or polyurea massesaccording to the invention individually or in the form of any desiredmixtures with one another and are optionally employed in amounts of0.001 to 5.0 wt %, preferably 0.002 to 2 wt %, calculated as the totalamount of catalysts employed based on the total amount of the startingcompounds employed.

The compositions according to the invention are preferably used toproduce transparent, compact moldings having a high refractive index.

The articles obtained from the compositions according to the inventionfeature very good light resistance even as such, i.e. without additionof appropriate stabilizers. Nevertheless, known UV-protectants (lightstabilizers) or antioxidants may be co-used as auxiliary and additiveagents C).

Suitable UV stabilizers C) are for example piperidine derivatives, forexample 4-benzoyloxy-2,2,6,6-tetramethylpiperidine,4-benzoyloxy-1,2,2,6,6-pentamethylpiperidine,bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate,bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate,bis(2,2,6,6-tetramethyl-4-piperidyl) suberate orbis(2,2,6,6-tetramethyl-4-piperidyl) dodecanedioate, benzophenonederivatives, for example 2,4-dihydroxy-, 2-hydroxy-4-methoxy-,2-hydroxy-4-octoxy-, 2-hydroxy-4-dodecyloxy- or2,2′-dihydroxy-4-dodecyloxybenzophenone, benzotriazole derivatives, forexample 2-(5-methyl-2-hydroxyphenyl)benzotriazole,2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole,2-(5-tert-octyl-2-hydroxyphenyl)benzotriazole,2-(5-dodecyl-2-hydroxyphenyl)benzotriazole,2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole,2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole,2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole,2-(3-tert-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole andesterification products of2-(3-tert-butyl-5-propionato-2-hydroxyphenyl)benzotriazole withpolyethylene glycol 300, oxalanilides, for example 2-ethyl-2′-ethoxy- or4-methyl-4′-methoxyoxalanilide, salicylic esters, for example phenylsalicylate, 4-tert-butylphenyl salicylate and 4-tert-octylphenylsalicylate; cinnamic ester derivatives, for example methylα-cyano-β-methyl-4-methoxycinnamate, butylα-cyano-methyl-4-methoxycinnamate, ethyl α-cyano-β-phenylcinnamate andisooctyl α-cyano-β-phenylcinnamate, or malonic ester derivatives, forexample dimethyl 4-methoxybenzylidenemalonate, diethyl4-methoxybenzylidenemalonate, and dimethyl 4-butoxybenzylidenemalonate.These light stabilizers may be employed either individually or in anydesired combinations with one another.

Suitable antioxidants C) are for example the known sterically hinderedphenols, for example 2,6-di-tert-butyl-4-methylphenol (lonol),pentaerythritoltetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate),octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, triethyleneglycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate,2,2′-thiobis(4-methyl-6-tert-butylphenol),2,2′-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate),which may be employed either individually or in any desired combinationswith one another.

Further auxiliary and additive agents C) for optional co-use are forexample the known flame retardants, for example trischlorethylphosphate, ammonium phosphate or polyphosphate, fillers, for examplebarium sulfate, diatomaceous earth, carbon black, whiting or elsereinforcing glass fibers.

Finally, it is also possible to co-use the internal mold release agents,dyes, pigments, hydrolysis inhibitors, fungistatic and bacteriostaticsubstances known per se.

It is particularly preferable when the composition according to theinvention contains as component C) at least one mold release agentselected from mono- and/or dialkyl phosphates and/or mono- and/ordialkoxyalkyl phosphates. As mono- and/or dialkyl phosphates,particularly mono- and/or dialkyl phosphates having 2 to 18 carbon atomsin the alkyl radical, preferably 8 to 12 carbon atoms, are. Particularlypreferred mono/dialkoxyalkyl phosphates have 2 to 12 carbon atoms in thealkoxyalkyl radical and up to three ether groups per alkoxyalkylradical, the abovementioned mono-/alkoxyalkyl phosphates having inparticular 4 to 10 carbon atoms in the alkoxyalkyl radical. Thepreferred mono-/dialkyl phosphates and mono-/dialkoxyalkyl phosphatesare particularly advantageous since in addition to their actual functionas a mold release agent they also have a favorable effect on thereaction rate in the reaction of the polyisocyanate component with thethiol component in the respect that their addition reduces the reactionrate of the two components with one another. This ultimately results inmolded articles of higher optical quality and in simpler handling of thecomposition after the mixing of the components.

Suitable mold release agents are for example methyl phosphate, dimethylphosphate, methoxyethyl phosphate, methoxypropyl phosphate,di(methoxyethyl) phosphate, methoxyethyl ethoxyethyl phosphate,methoxyethyl propoxyethyl phosphate, di(methoxypropyl) phosphate, ethylphosphate, diethyl phosphate, ethoxyethyl phosphate, di(ethoxyethyl)phosphate, ethoxypropyl phosphate, ethoxyethyl propoxyethyl phosphate,di(ethoxypropyl) phosphate, ethoxyethyl butoxyethyl phosphate, isopropylphosphate, diisopropyl phosphate, propoxyethyl phosphate,di(propoxyethyl) phosphate, propoxypropyl phosphate, di(propoxylpropyl)phosphate, butyl phosphate, dibutyl phosphate, butoxyethyl phosphate,butoxypropyl phosphate, di(butoxyethyl) phosphate, pentoxyethylphosphate, bis(2-ethylhexyl) phosphate, di(hexyloxyethyl) phosphate,octyl phosphate, dioctyl phosphate, decyl phosphate, isodecyl phosphate,diisodecyl phosphate, isodecyloxyethyl phosphate, di(decyloxyethyl)phosphate, dodecyl phosphate, didoceyl phosphate, tridecanol phosphate,bis(tridecanol) phosphate, stearyl phosphate, distearyl phosphate andany desired mixtures of such compounds.

The compositions according to the invention advantageously contain 0.01to 4 wt % of mono-/dialkylphosphates and/ormono-/dialkylalkoxyphosphates, preferably 0.02 to 2 wt %, based on theoverall composition. The abovementioned usage amounts relate to thetotal content of these substances as mold release agents.

A particularly preferable composition according to the invention forproducing transparent polythiourethane articles contains or consists of

-   -   A) 35 to 65 wt % based on the composition, in particular 45 to        55 wt %, of a polyisocyanate component containing    -   at least 90 to 99.8 wt %, in particular 95 to 99.7 wt %, based        on the polyisocyanate component of a polyisocyanate selected        from 1,3-XDI and/or 1,4-XDI having a functionality of isocyanate        groups of 2 per molecule and 0.05 to 2 wt %, in particular 0.1        to 1 wt %, based on the polyisocyanate component of        3-(isocyanatomethyl)benzonitrile and/or        4-(isocyanatomethyl)benzonitrile,    -   B) 35 to 65 wt % based on the composition, in particular 45 to        55 wt %, of a thiol component containing at least one polythiol        having a functionality of thiol groups of at least 2 per        molecule, wherein the thiol component in particular consists of        a polythiol having a functionality of thiol groups of 3 per        molecule, namely DMPT        (4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane),    -   and    -   C) auxiliary and additive agents comprising 0.01 to 4 wt %, in        particular 0.02 to 2 wt %, of a mold release agent selected from        mono- and/or dialkyl phosphates having 2 to 18 carbon atoms in        the alkyl radical and/or mono- and/or dialkoxyalkyl phosphates        having 2 to 12 carbon atoms in the alkoxyalkyl radical and up to        three ether groups per alkoxyalkyl radical,    -   wherein the ratio of isocyanate groups to isocyanate-reactive        groups is 0.5:1 to 2.0:1,    -   wherein the composition is characterized in that    -   the composition further contains as component D) 0.005 to 10 wt        % based on the entire composition of at least one aromatic        nitrile selected from 3-(isocyanatomethyl)benzonitrile and/or        4-(isocyanatomethyl)benzonitrile, in particular 0.01 to 5 wt %.

The present invention further provides a process for producingtransparent polythiourethane articles by reaction of a compositioncontaining or consisting of

-   -   A) a polyisocyanate component containing at least one        polyisocyanate having a functionality of isocyanate groups of at        least 2 per molecule,    -   B) a thiol component containing or consisting of at least one        polythiol having a functionality of thiol groups of at least 2        per molecule    -   and optionally    -   C) auxiliary and additive agents,    -   wherein the ratio of isocyanate groups to isocyanate-reactive        groups is 0.5:1 to 2.0:1,        wherein the process is characterized in that the composition        further contains    -   D) at least one aromatic nitrile.

The preferred embodiments and definitions set out above applyanalogously to the compositions employed in the process according to theinvention.

The process may in particular be performed without solvent addition,i.e. in solvent-free fashion, and the nitrile addition is not to beunderstood as solvent addition in this context.

Irrespective of the type of chosen starting substances in the processaccording to the invention the reaction of the polyisocyanate mixturesA) with the thiol component B) and optionally furtherisocyanate-reactive components is effected adhering to an equivalentratio of isocyanate groups to isocyanate-reactive groups of 0.5:1 to2.0:1, preferably of 0.7:1 to 1.3:1, more preferably of 0.8:1 to 1.2:1.

In the process according to the invention the components of thecomposition according to the invention are preferably mixed, optionallyin solvent-free form, in the abovestated equivalent ratio of isocyanategroups to isocyanate-reactive groups using suitable mixing apparatusesand charged into open or closed molds by any desired method, for exampleby simple hand-pouring but preferably using suitable machines, forexample the low-pressure or high-pressure machines customary inpolyurethane technology, or by the RIM process. Curing may be performedin a temperature range of 40° C. to 180° C., preferably of 50° C. to140° C., particularly preferably of 60° C. to 120° C., and optionallyunder elevated pressure of up to 300 bar, preferably up to 100 bar,particularly preferably up to 40 bar.

The polyisocyanates and optionally also the other starting componentsmay be degassed by application of vacuum.

The molded articles thus produced from the according to the inventioncan generally be demolded after a short time, for example after 2 to 60min. A post-curing at a temperature of 50° C. to 100° C., preferably at60° C. to 90° C., may optionally follow.

Compact light- and weather-resistant polythiourethane articles havinghigh resistance toward solvents and chemicals and outstanding mechanicalproperties, in particular an excellent heat resistance even at highertemperatures of for example 80° C., are obtained in this way. Comparedto the prior art systems which do not contain aromatic nitriles themolded articles according to the invention feature a lower propensityfor formation of cloudiness.

The present invention further provides a compact transparentpolythiourethane article obtainable by reaction of the components of thecomposition according to the invention. This polythiourethane articlemay be a glass-replacement part, an optical, optoelectronic orelectronic component part, an optical lens or a spectacle glass.Specific applications are for example production of/use asglass-replacement panes, for example sunroofs, front, rear or side panesin automotive or aeronautical production, as safety glass, solarmodules, light emitting diodes, lenses or collimators, as are employedfor example as auxiliary optics in LED lamps or automotive headlamps.

However, a particularly preferred field of application for the moldedpolythiourethane articles according to the invention obtainable from thecompositions according to the invention is the production of lightweightplastic spectacle glasses having a high refractive index and a high Abbenumber. Spectacle glasses produced according to the invention featureoutstanding mechanical properties, in particular hardness and impactresistance and also good scratch resistance and are moreover easy toprocess and colorable as desired.

The present invention further relates to the use of aromatic nitrilesfor producing transparent polythiourethane articles.

The present invention further provides a mixture of a polyisocyanatehaving a functionality of isocyanate groups of at least 2 per moleculeand at least one aromatic nitrile for producing compact transparentpolythiourethane articles.

The invention will now be more particularly discussed with reference toexemplary embodiments.

FIG. 1 depicts a schematic diagram of a suitable plant for gas-phasephosgenation. This plant is particularly suitable for manufacturing1,3-XDI and 1,4-XDI with contents of nitriles >0.1 wt % based on themanufactured isocyanate.

All percentages are based on weight, unless stated otherwise.

The NCO contents were determined by titrimetry as per DIN EN ISO 11909.

Measurement of the refractive indices and Abbe numbers was effectedusing a Zeiss Model B Abbe refractometer as per DIN EN ISO 489:1999-08.

Transmission and haze measurements as per ASTM D 1003 were performedwith a Byk Haze-Gard Plus using standard light type D65 (defined in DIN6173).

The chemicals used were employed without further pretreatment:

Tinuvin® 571: alkylphenol-substituted benzotriazole (BASF)

Zelec UN: mixture of long-chain mono- and dialkyl phosphate (Steppan)

DBC: dibutyltin dichloride (Acros Organics)

DMPT: 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (Bruno Bock GmbH)

Desmodur W: H12-MDI, NCO functionality 2 (Bayer MaterialScience AG)

Benzonitrile (Merck KGaA)

Performing the gas-phase phosgenation of 1,3-XDA

EXAMPLE 1

In a plant for gas-phase phosgenation comprising an amine evaporationstage as per FIG. 1, a tubular reactor (L: 9350 mm, internal diameter134.5 mm) having a coaxial nozzle arranged along the reactor axis(internal diameter 134.5 mm) and a downstream isocyanate condensationstage, 200 kg/h of 1,3-XDA were continuously evaporated at a pressure of650 mbar abs. with introduction of a nitrogen stream of 10 kg/h, thetemperature in the pumped circulation circuit (3200 kg/h) being kept at150° C. by cooling in a heat exchanger (WT). 500 ppm Tinuvin® 571 hadpreviously been added to the pumped circulation circuit. The supplytemperature to the evaporator (V) was 255° C., the entry temperature ofthe cooling medium into the heat exchanger (WT) was 40° C. and theaverage residence time of the 1,3-XDA in the pumped circulation circuitwas 35 minutes. After exiting the evaporator the stream composed ofgaseous 1,3-XDA and nitrogen was heated to 280° C. in a further heatexchanger and supplied to the reactor via the coaxial nozzle.Simultaneously and in parallel thereto, 750 kg/h of phosgene were heatedto 310° C. and on the annular space left free by the nozzle likewisecontinuously supplied to the reactor in which the two reactant streamswere mixed and brought to reaction. The velocity of the gas stream inthe reactor was about 20 m/s and the velocity ratio of theamine/nitrogen stream to the phosgene stream was 8,8. The pressure atthe vacuum pump was 600 mbar abs.

After an average residence time in the reactor of 0.48 seconds the gasstream containing the reaction product 1,3-XDI was cooled by injectioncooling with monochlorobenzene and condensed, the temperature of theliquid phase in the quench being about 90° C. The content of3-chloromethylbenzyl isocyanate determined by gas chromatography was0.4% based on the sum of 1,3-XDI and 3-CI-XI. The reaction mixture wasthen freed of HCl and phosgene and worked up by distillation. The yieldof 1,3-XDI was 95% of theory.

EXAMPLE 2

In the above described plant 160 kg/h of 1,3-XDA were analogouslyevaporated at a pressure of 500 mbar abs. with introduction of anitrogen stream of 4 kg/h, the temperature in the pumped circulationcircuit (3200 kg/h) being kept at 150° C. by cooling in a heat exchanger(WT). 500 ppm Tinuvin © 571 had previously been added to the pumpedcirculation circuit. The supply temperature to the evaporator (V) was240° C., the entry temperature of the cooling medium into the heatexchanger (WT) was 40° C. and the average residence time of the 1,3-XDAin the pumped circulation circuit was 43 minutes. The stream composed ofgaseous 1,3-XDA and nitrogen was heated to 280° C. in a further heatexchanger and supplied to the reactor via the coaxial nozzle.Simultaneously and in parallel thereto, 500 kg/h of phosgene were heatedto 310° C. and on the annular space left free by the nozzle likewisecontinuously supplied to the reactor in which the two reactant streamswere mixed and brought to reaction. The velocity of the gas stream inthe reactor was about 20 m/s and the velocity ratio of the amine streamto the phosgene stream was 8.8. After an average residence time in thereactor of 0.46 seconds the gas stream containing the reaction product1,3-XDI was cooled by injection cooling with monochlorobenzene andcondensed, the temperature of the liquid phase in the quench being about90° C.

The content of 3-chloromethylbenzyl isocyanate determined by gaschromatography was 0.3% based on the sum of 1,3-XDI and 1.3-CI-XI. Thereaction mixture was then freed of HCl and phosgene and worked up bydistillation. The yield of 1,3-XDI was 92% of theory.

Production of 1,3-XDI manufactured by liquid-phase phosgenation

EXAMPLE 3

With stirring and cooling a solution of 5 parts by weight of 1,3-XDA in50 parts by weight of monochlorobenzene was metered into a solution of20 parts by weight of phosgene in 25 parts by weight ofmonochlorobenzene at 0-10° C. and on completion of the addition themixture was allowed to reach room temperature. The temperature wassubsequently increased to reflux with introduction of phosgene accordingto gas evolution and phosgenation was continued until the solutioneventually became clear. Once the clear point had been reached (about4-5 h) phosgenation was continued for a further 30 minutes. Phosgeneintroduction was then terminated and the mixture was refluxed withintroduction of nitrogen until phosgene was no longer detectable in theoffgas.

The reaction mixture was then worked up by distillation to obtain XDI asa colorless liquid having a boiling point of 130° C./0.2 mbar. The yieldof 1,3-XDI was 80% of theory

EXAMPLE 4

2 kg of the XDI obtained in example 2 were fractionally distilledthrough a column. The first 500 g were discarded as forerun and 1 kg ofcolorless 1,3-XDI was obtained as the main fraction. This fraction wasadmixed with 1.4 g of Zelec UN (Steppan) at room temperature and left tostand for 24 h. The HC content of the sample after distillation,measured as per ASTM specification D4663-98, was 105 ppm. The content of3-isocyanatomethylbenzonitrile was determined by dissolving 1 g of1,3-XDI in 100 ml of acetonitrile. 100 μl of this solution were mixedwith 900 μl of a diethylamine solution (0.2 g of diethylamine in 100 mlof acetonitrile) and stored at 65° C. for 30 minutes prior to HPLC-MSmeasurement. Purity was determined by integration of the areas of thesignals in the UV spectrometer. It was assumed that all compounds showthe same UV absorption and that no compounds without a UV absorption arepresent in the samples. A further assumption was that no degradationreactions take place during measurement. The following program waschosen for HPLC-MS measurement:

Synapt G2-S HR-MS, ACQUITY UPLC (Waters) QS. No.: 02634

UV: PDA (Total Absorbance Chromatogram)

Column: Kinetex 100×2.1 mm_1.7 μm

Column temperature: 30° C.

The mobile phase consisted of:

Solvent: A) water+0.05% formic acid

B) acetonitrile+0.05% formic acid

Flow rate: 0.5 ml/min

Gradient: t0/5% B_t0.5/5% B_t6/100% B_t7/100% B_t7.1/5% B_t8/5% B

The sample was found to contain 98.4% 1,3-XDI and 0.7%3-isocyanatomethylbenzonitrile.

EXAMPLE 5

2 kg of the XDI obtained in example 3 were fractionally distilledthrough a column. The first 800 g were discarded as forerun and 700 g ofcolorless 1,3-XD1 were obtained as the main fraction. This fraction wasadmixed with 0.98 g of Zelec UN at room temperature and left to standfor 24 h. The HC content of the sample after distillation, measured asper ASTM specification D4663-98, was 108 ppm. Analogously to example 4,purity determination by HPLC was performed. No3-isocyanatomethylbenzonitrile was found in the course of this. Theproportion of 1,3-XDI was 95.4%.

Production of polythiourethane articles:

EXAMPLE 6

In a flask, 0.002 g of dibutyltin dichloride (DBC) were dissolved in94.59 g of 1,3-XDI from example 4 and the mixture was evacuated at 10mbar for 30 minutes. 90.00 g of DMPT(4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane) were then added intothe flask and the final mixture was stirred and degassed at 10 mbar for30 minutes. The mixture was then filtered through a 5 μm filter, drawninto a syringe and the casting mold was completely filled therewith. Thecasting mold was prepared by clamping together two glass shell molds (85mm diameter, internal radius 88 mm, Shamir Insight, Inc., IL) with a gapof 8 mm and a plastic sealing ring to form a casting cavity. The moldgap is 8 mm at each point of the lens.

The filled casting mold was cured in a drying cabinet with thetemperature profile: 15 hours at 65° C.; 2 hours at 100° C. and afurther 2 hours at 120′C. The casting mold was then cooled to roomtemperature and, after complete cooling, first the sleeve and then thetwo glass articles were manually removed.

A spectacle glass blank that was completely clear, transparent and freefrom cloudiness was obtained in this way.

Transmission was 90.3% for standard light type D65, haze was 2.1. Therefractive index nE was 1.67 at 23° C.

EXAMPLE 7

Analogously to example 6 a spectacle glass blank was produced using1,3-XDI from example 5. This spectacle glass blank was completelycloudy, transmission was only 29.7%, haze was 100.

EXAMPLE 8

In a flask, 94.59 g of 1,3-XDI from example 5 were admixed with 9.25 gof benzonitrile, 0.002 g of dibutyltin dichloride (DBC) were dissolvedtherein and the mixture was evacuated at 10 mbar for 30 minutes. 90.00 gof DMPT (4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane) were thenadded into the flask and the final mixture was stirred and degassed at10 mbar for 30 minutes. The mixture was then subsequently subjected tofurther processing as in example 6 to afford a spectacle glass blank.

A spectacle glass blank that was completely clear, transparent and freefrom cloudiness was obtained in this way.

Transmission was 86.3% for standard light type D65, haze was 2.9. Therefractive index nE was 1.67 at 23° C.

EXAMPLE 9

In a flask, 0.011 g of dibutyltin dichloride (DBC) were dissolved in131.00 g of Desmodur W, 10.89 g of benzonitrile and 1.31 g of Zelec UNand the mixture was evacuated at 10 mbar for 30 minutes. 85.50 g of DMPT(4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane) were then added intothe flask and the final mixture was stirred and degassed at 10 mbar for30 minutes. 20 g of the mixture were then added to a closable PP beaker(75 g ointment pot, internal diameter 50 mm) and cured in a dryingcabinet with the temperature profile: 8 hours at 65° C.; 2 hours at 100°C. and a further 6 hours at 120° C. The casting mold was then cooled toroom temperature and, after complete cooling, the casting was demolded.The casting was free from cloudiness and transparent.

EXAMPLE 10

In a flask, 0.22 g of dibutyltin dichloride (DBC) were dissolved in131.00 g of Desmodur W and 2.6 g of Zelec UN and the mixture wasevacuated at 10 mbar for 30 minutes. 85.50 g of DMPT(4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane) were then added intothe flask and the final mixture was stirred and degassed at 10 mbar for30 minutes. 20 g of the mixture were then added to a closable PP beaker(75 g ointment pot, internal diameter 50 mm) and cured in a dryingcabinet with the temperature profile: 8 hours at 65° C.; 2 hours at 100°C. and a further 6 hours at 120° C. The casting mold was then cooled toroom temperature and, after complete cooling, the casting was demolded.The casting was milky-white.

1.-15. (canceled)
 16. A composition for producing transparentpolythiourethane articles comprising A) a polyisocyanate componentcontaining at least one polyisocyanate having a functionality ofisocyanate groups of at least 2 per molecule, B) a thiol componentcontaining at least one polythiol having a functionality of thiol groupsof at least 2 per molecule and optionally C) auxiliary and additiveagents, wherein the ratio of isocyanate groups to isocyanate-reactivegroups is 0.5:1 to 2.0:1, wherein the composition further contains D) atleast one aromatic nitrile.
 17. The composition as claimed in claim 16,wherein the composition contains 0.0025 to 10 wt % based on the entirecomposition of aromatic nitrile.
 18. The composition as claimed in claim16, wherein the nitrile contains at least one further functional group,in particular an isocyanate group.
 19. The composition as claimed inclaim 16, wherein the nitrile is selected from the group consisting ofbenzonitrile, 3-(isocyanatomethyl)benzonitrile,4-(isocyanatomethyl)benzonitrile, 3-(chloromethyl)benzonitrile,4-(chloromethyl)benzonitrile and mixtures thereof.
 20. The compositionas claimed in claim 16, wherein the polyisocyanate is selected from thegroup consisting of 1,3-bis(isocyanatomethyl)benzene (1,3-XDI),1,4-bis(isocyanatomethyl)benzene (1,4-XDI),2,5-bis(isocyanatomethyl)bicyclo[2.2.1]heptane,2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane,1,4-bis(isocyanatomethyl)cyclohexane,1,3-bis(isocyanatomethyl)cyclohexane,2,2′-diisocyanatodicyclohexylmethane,2,4′-diisocyanatodicyclohexylmethane,4,4′-diisocyanatodicyclohexylmethane (H12-MDI),1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophoronediisocyanate; IPDI) and mixtures thereof.
 21. The composition as claimedin claim 16, wherein the polyisocyanate is an aromatic polyisocyanateand the nitrile is derived from the same polyamine as thepolyisocyanate.
 22. The composition as claimed in claim 20, wherein thepolyisocyanate is selected from 1,3-bis(isocyanatomethyl)benzene(1,3-XDI) and the nitrile from 3-(isocyanatomethyl)benzonitrile and/orthe polyisocyanate is selected from 1,4-bis(isocyanatomethyl)benzene(1,4-XDI) and the nitrile from 4-(isocyanatomethyl)benzonitrile.
 23. Thecomposition as claimed in claim 16, wherein the polythiol is selectedfrom group consisting of4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane,2,5-bismercaptomethyl-1,4-dithiane,1,1,3,3-tetrakis(mercaptomethylthio)propane,5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane,trimethylolpropane tris(3-mercaptopropionate), trimethylolethanetris(2-mercaptoacetate), pentaerythritol tetrakis(2-mercaptoacetate),pentaerythritol tetrakis(3-mercaptopropionate) and mixtures thereof. 24.The composition as claimed in claim 16, wherein as component C)catalysts, surface-active agents, UV stabilizers, antioxidants,fragrances, mold release agents, fillers and/or pigments are employed.25. The composition as claimed in claim 24, wherein the mold releaseagent is a phosphate ester.
 26. The composition as claimed in claim 24,wherein the mold release agent is a mono- and/or dialkoxyalkyl phosphatehaving 2 to 12 carbon atoms in the alkoxyalkyl radical and up to threeether groups per alkoxyalkyl radical.
 27. A process for producing atransparent polythiourethane article comprising reacting a compositioncomprising A) a polyisocyanate component containing at least onepolyisocyanate having a functionality of isocyanate groups of at least 2per molecule, B) a thiol component containing at least one polythiolhaving a functionality of thiol groups of at least 2 per molecule andoptionally C) auxiliary and additive agents, wherein the ratio ofisocyanate groups to isocyanate-reactive groups is 0.5:1 to 2.0:1,wherein the composition further contains D) at least one aromaticnitrile.
 28. A compact and transparent polythiourethane article obtainedby reaction of the components of a composition as claimed in claim 16.29. A mixture of a polyisocyanate having a functionality of isocyanategroups of at least 2 per molecule and at least one aromatic nitrile forproducing compact transparent polythiourethane articles.